Resurrecting unused locomotives

There are many reasons you might need to bring a locomotive back to life. Here are some tips for resurrecting unused locomotives.

Photo of weathered dark blue six-axle road unit on white background — Whether a recent purchase of an old locomotive, or one that’s been sitting on your shelves for awhile, resurrecting unused locomotives is easy to do following these steps.

Disassembly

Color photo showing mechanism of HO scale diesel locomotive. — This Walthers HO scale SD9 mechanism shows the parts of a contemporary model. Note the can motor and the addition of electronics. The mechanical parts are still largely the same as older models, though, and the advice for cleaning and lubrication remains the same.

The first thing you’ll need to do is to get inside the locomotive shell. Maybe you’re lucky enough to have an exploded-view diagram of your model. If not, you can check the manufacturer’s website. Many offer diagrams as PDFs you can view or download.
If your model is older, you might need to do some research. Here are a couple of sites to try: for HO scale, check out HO Seeker. For N scale, try spookshow.net. For some general tips on disassembling locomotives, see this story on Trains.com.

Clean the gearbox

Once you’ve removed the shell, clean the old grease out of the gearbox. On a diesel, the power trucks usually clip or snap into the frame.

mechanism of N scale diesel locomotive — The Atlas N scale EMD GP40-2 features a split-frame mechanism. Plastic clips instead of mechanical fasteners are used to hold the two halves of the frame together.

On split-frame N scale models, the trucks will fall free after the frame halves are split.
Oftentimes, a clip on the top or bottom of the power truck will hold the halves together. Once you remove the clips, you can take out the wheels. They may have bronze bearing blocks on the axles.
With the wheels out of the way, lay the truck on its side, then take the halves apart. Placing the truck on its side prevents the gears from falling out. If they stay stuck into one side of the truck, that’s a good indication the grease or oil has started to solidify. That’s what you want to get rid of. Be sure to note where the various gears go so you can put them back together correctly.

Partially disassembled Athearn diesel locomotive showing frame and truck worm gear — To remove the truck of a classic Athearn diesel locomotive, move the contact strap out of the way, then pry the worm gear cover off the top of the truck with a flat screwdriver. You can now maneuver the truck out of the frame.

Clean everything with paper towels. You don’t need to use solvent, but you might want to use toothpicks or cotton swabs to get in the corners, crevices, and between the teeth of the gears. Don’t use metal tools that could scratch the gears.
Once everything is clean, begin the reassembly process. Everything should slide together easily. Make sure there’s no binding by rolling the gears back and forth. If there’s a worm gear involved, turn that to get the gears to rotate. Look and feel for binding. If you notice any, take things apart until the binding is gone.
With everything working smoothly, sparingly add lubrication. If the manufacturer includes instructions for lubricating the model, follow those. But generally, you want to be sparing with new lubricant. A single drop of plastic-compatible oil where the gears spin on an axle, and maybe a dab of grease on one gear is

Bottom of three-axle HO scale diesel truck showing wheels and gears — Plastic clips hold the Athearn truck together. There are two on the top and one on the bottom. Once the large clip on the bottom is removed, you can see the drive gears, axles, and bearing blocks. Lift the wheel/axle assemblies out of the truck and wipe off excess oil.

sufficient. One of the primary suppliers is Labelle Industries, and we offer kits for HO and N scale locomotive work.

If you’re working on a steam locomotive, avoid disassembling the running gear as much as possible, especially on plastic models. The side rods and valve gear are often riveted together, and aren’t intended to come apart. If there’s a cover plate below the drivers, you can often remove it without causing complications. Use toothpicks to clear out as much hardened lubrication as you can, and add a few drops of oil to the driver axles on the inside of the frame. Most steam locomotives have one driver connected to the motor with a gearbox, then the motion of the side rods transfers power to the rest of the wheels. Some older N scale steam locomotives will have a gear train similar to what’s used on diesels. Clean the gears up as best you can, then add just a tiny amount of oil to keep things running smoothly.

Three-axle diesel truck halves with exposed gearsets — Inside the Athearn truck you’ll find a series of gears spinning on posts molded into one half of the gear case. Grease, oil, and dirt can build up inside this case on older models that have seen lots of service. And on locomotives that have never been run, the grease and oil can start to solidify. Use paper towels, cotton swabs, and toothpicks to remove the dirt and hardened grease. Take photos with your phone or make notes to ensure you replace the gears in the correct location. Usually, there’s only one way things can go together.

Check the motor

While the trucks are out of the model, spin the motor to make sure it isn’t binding. If there’s significant resistance to turning the motor shaft, you may have to replace it. Check the manufacturer’s website to see if you can purchase a replacement. If the manufacturer doesn’t offer replacement motors, or if it’s an older model from a defunct manufacturer, check out NorthWest Short Line. The company offers wheels, gears, nuts, bolts, washers, screws and all sorts of repair and replacement parts for model locomotives.

Clean the wheels

Next, take a look at the locomotive’s drive wheels. If they’re dirty, you can use various cleaners to get them shiny again. Though some people use alcohol on a cotton swab, there’s evidence this can leave residue that will increase the amount of micro-arcing that goes on between the wheels and rails as the wheels roll along

Metal wheelset with black plastic gear and bronze bearing blocks — After removing the wheelsets, check the gears for defects such as flash, or in older locomotives, cracks. Athearn locomotives tend to be fine, but some Life-Like Proto2000 locomotives manufactured in the 1990s had a tendency to have cracked gears. The Athearn 60024 gear will work on those locomotives.

with power traveling across the connection. Other solvents, such as mineral spirits, seem to do as good a job cleaning and leave less residue. You can also use electronic contact cleaner.
While you’re working on the wheels, make sure the power path from the wheels back to the rest of the locomotive is in order. Some models direct power through the frame. Ensure the contact points are clean and polished. Check that any wheel or axle wipers are properly positioned to make contact, and that any wiring connections are solid. You may need to do some gentle bending of contacts or repair some wiring connections with solder.

Reinstall the trucks

With the trucks reassembled, you can reinstall them on the locomotive. Again, make sure the wiring path is complete, and that there’s no binding as you reassemble the model. Most diesel models have a centrally mounted motor with drive shafts going to each truck. These parts are usually made from slippery engineering plastic that doesn’t require lubrication. All that adding lubricants will accomplish is coating the inside of your model in a fine layer of oil, which will do a great job of sticking dust and dirt to the moving parts and electronics inside the shell.

An open-frame motor showing commutators and flywheel — Some older models, such as this Athearn “blue box” diesel, have open-frame motors where you can see the armature windings and the commutator pads. These pads can get dirty from the action of the brushes rubbing against them. Clean the dirt off with a pencil eraser. On can motors, the only maintenance possible is a drop of oil on the motor shaft bearing. Use plastic-compatible oils just in case there are unseen plastic parts inside the motor.

Check the couplers

Now that you’ve put the chassis back together, give it a try on your test track. If everything works as you expect, you can reinstall the chassis in the locomotive shell. The last mechanical thing you’ll need to check is the coupler height. Use a Kadee or Micro-Trains Line coupler height gauge.
Most likely, the couplers will be at the correct height. Make sure they don’t sag or droop, and that the trip pin is at the correct height. I’ve used Kadee’s fiber washers to keep couplers from flopping around in their draft-gear boxes. You can also use them if your couplers are too high to shim the draft-gear box lower, assuming the draft-gear box is a separate part.
If the draft-gear box is molded to the chassis or body shell, you may have to replace the couplers with underset or overset shank versions. See the Kadee and Micro-Trains Line websites for options.

Dusting

While the shell is off the chassis, it’s a good time to give it a thorough cleaning. If it’s just dusty, use soft brushes and canned air for cleaning electronics to remove loose dirt. If the dust is stubborn, use a soft toothbrush and some mild soap. Be careful not to knock off any details. You may consider working over a shallow pan to catch any parts that may come off.

Detail repairs

With everything cleaned and running well, the last step is to repair broken or missing details. Again, check the manufacturer’s website to see if replacement parts are available. If they’re not, you might find what you need from some of the detail parts manufacturers such as Detail Associates (they don’t have a website, but you’ll find their parts on many retail sites), Details West, or Cal Scale, among others.
With everything back together, you can enjoy your new old locomotive!